Electrical and optical properties of Zr1−xAlxN thin films

Zr1−xAlxN thin films, with 0≤x≤0.73, have been synthesized by magnetron sputtering. The phases and the electrical and optical properties have been investigated. For x≤0.43, the Zr1−xAlxN films crystallize in cubic NaCl type of structure (B1 type), while at higher Al content, 0.43<x≤0.73, the films contain two phases: the cubic ZrN and the hexagonal AlN phases poorly crystallize. Here, we report on the physical properties of the ternary single-phase Zr1−xAlxN compounds as a function of x over the range 0≤x≤0.43. The optical and the electrical properties of the B1-Zr1−xAlxN films depend on x. The effective density N* of conduction electrons and the free charge carrier scattering time τ decrease monotonously as the Al content increases, whereas the room-temperature dc resistivity measured by the van der Pauw method increases from 260 to 2260 μΩ cm for x=0.43. The observed trends are correlated with changes in the electronic structure due to the substitution of Zr by Al atoms. The optical properties are well described by a Drude–Lorentz model, while a straightforward model of phonon-alloy scattering and grain boundary scattering account for the electronic transport properties.